A number of feed systems for gas and liquid phase and fluidized reactors are known to those skilled in the art. Well known systems include systems comprising a catalyst storage vessel connected to a feed chamber with filling and emptying valves in turn connected to a reactor. Typically the catalyst is conveyed from the storage vessel through the catalyst feed system to the reactor by maintaining the reactor at a pressure lower than that in the system. Valves incorporated in such systems allow a given quantity of catalyst to move from the storage vessel to a feed chamber or metering device and then to the reactor.
U.S. Pat. No. 4,610,574 discloses an apparatus comprising an enclosed mixing tank with rotating mixing blades and a rotatable shot valve spaced below the mixing tank. The shot valve can be rotated from a first position in communication with an opening in the lower portion of the mixing tank to a second position in communication with a hydrocarbon feed conduit that provides hydrocarbon liquid to the polymerization reactor vessel. A bypass conduit is provided for introducing hydrocarbon liquid from the hydrocarbon feed conduit into the mixing tank wherein the interior of the mixing tank is maintained at the same pressure as the hydrocarbon feed conduit.
U.S. Pat. No. 4,767,028 discloses a rotating metering valve having a transverse passage which carries a slidable piston reciprocating once for each revolution of the valve for metering particulate material from an inlet port to an outlet port and a purge fluid port in the transverse passage.
U.S. Pat. No. 5,240,683 discloses a devise comprising a storage vessel for a catalyst and a metering valve having a cavity in which the metering valve receives the catalyst powder and is rotated to deliver the catalyst powder to an intermediate chamber having a gas flow to suspend the catalyst prior to discharging the suspended catalyst powder into a pipe with a transverse gas flow to direct the catalyst powder into a reactor vessel.
U.S. Pat. No. 5,851,493 discloses an injection system, for feeding a particulate material into a process vessel, including a valve with at least one cavity for receiving a predetermined volume of particulate material and a sweep stream source for providing a sweep stream having a flow direction generally toward the cavity to remove substantially all of the particulate material from the cavity of the valve.
U.S. Pat. No. 6,319,995 discloses a method of delivering a dry catalyst to a liquid-filled polymerization reactor by transferring dry catalyst from a reservoir to a catalyst chamber and introducing an inert fluid into the chamber to flush the catalyst charge toward the reactor.
Additional references of interest include: U.S. Pat. Nos. 3,012,024; 3,167,398; 3,846,394; 4,123,601; 4,687,381; 4,774,299; 4,773,565; and 5,433,924.
There exists a need for a valve assembly having a filter in the valve passage for use in a particulate material feed system that provides consistent uniform particulate material feed and consistent volume fill efficiency in a chemical process, particularly for use in providing a catalyst in a polymerization process. There exists a need for a valve assembly having a filter in the valve passage for use in a particulate material metering system and/or feed system in which the process of using the filter flushes the particulate material from the filter.